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Discussion in 'General Technical Questions and Answers' started by KC9AWD, Jan 24, 2004.

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  1. KC9AWD

    KC9AWD Ham Member QRZ Page

    Hello everyone I have a beautiful Alliance HD-73 rotor system the rotor itself is still new in the box and the control box looks great and works great EXCEPT for the meter it doesnt move and ive been told its a common problem i even bought 2 on ebay with exact same problem and i sent it to a guy and he cant find a meter to fix it,, now i have 3 control boxes 1 rotor and cant use any of it!!!  [​IMG]

    any ideas on a 6 wire box i cold use in place of the alliance ?
  2. KD7WHQ

    KD7WHQ QRZ Member QRZ Page

    You sure it's the meter in the control head?
    If it doesn't indicate on a second head, I'd say the pot in the rotor has a problem.

    An ohm meter across the leads on the connector board on the rotor would be the easiest way to check. If it doesn't show a open, run the rotor to a limit, and check again. If it changed, it's either the wiring, or the control.

    If it didn't, it's the pot.

    On the control head, shunt the pot connections with a paperclip momentarily. The meter should deflect.

    If you needs parts, look up Norm's Rotor Service. He picked up the entire inventory when Alliance closed up, and if he doesn't have it, it's going to be hard to find..
  3. WA2ZDY

    WA2ZDY Guest

    As KD7WHQ alluded, the direction indicator is a meter in series with a pot in the rotor. The position of the pot controls the current flowing through the meter. So the meter, the pot and the wiring all need to be intact for it to work. Do the checks WHQ suggested and also inspect your wiring. Be sure there are no defects in the cable between the controller and rotor.

    I can't see three controllers with the same - simple - defect. I see the pot in the rotor housing being crummed up or ruined by weather leakage. I also see maybe a broken line in the control cable.

    Double check, it's a simple circuit and should be a simple fix.

    Good luck.
  4. KC7UP

    KC7UP Ham Member QRZ Page

    I have a HD73 and a HD73a Alliance rotors and control boxes. Have owned and used them since 1980 and never had a problem with the meters. You do have to take the rotors apart occasionally and clean and regrease the bearings. That the fun part aligning all the individual balls around the rotor.
  5. KM5FL

    KM5FL Ham Member QRZ Page

    I just finished repairing an HD-73 control box with the same problem.. There are two diodes (1N34) connected across terminals 2 & 3 of the rotor cable terminal strip.. If either of those diodes are bad, the meter will not indicate..

  6. KD7WHQ

    KD7WHQ QRZ Member QRZ Page

    KM5FL, if he checks the pot, he is going to find it open.
    The same problem on three control heads on the same rotor rather bear it out.
    And, having taken mine apart and lubing it, the only fix for the pot is a replacement.
    Wanna put a wager on he shunts the connections on all three heads and the meter swings to full? [​IMG]
    It's, as said, a simple ohm meter circuit. Complete with a zero adjustment..


    And I guess you didn't use FoMoCo certified molydisulfide grease when you lubed yours.. No problem with the balls at all. Stuck right in there. [​IMG]

    Something else to watch for if you take that HD-73 apart; 200 balls between two races. I strongly suggest you get a good grease before you take it apart. Molydisulfide based would be a good choice, at least in my opinion.

    The HD-73 would easily turn your car, if centered, but only once, maybe completely. It is rated for more than 1,000 pounds of centered load, but would make a valiant try with the car. [​IMG] Obviously far more than you would ever put on it at any rate..
  7. KM5FL

    KM5FL Ham Member QRZ Page

    HEY William, or is it Bill...

    Don't get so huffy. I wasn't disputing your word or criticizing your troubleshooting directions.. I was simply adding an additional item that could be the problem.. I learned a long time ago when troubleshooting for a problem, never assume anything...

    I certainly hope your remarks about the proper grease to use was directed at someone else, as I never mentioned anything about bearings or grease.....

    And as for placing wagers??? I don't do that either..

  8. KC7UP

    KC7UP Ham Member QRZ Page

    I never said it was hard to hold the balls around the rotor housing, I said that was the fun part. I used the correct grease although it certainly didn't specify your brand. [​IMG] The unfun part is taking down the tower, even though its a tilt over, and then taking the antenna off etc.
  9. W9GB

    W9GB Ham Member QRZ Page

    Gary -

    I think you need to talk to Norm's Rotor Service, who purchased all of the Alliance inventory, repairs these units and has virtually every part for Alliance models.

    FAQ about Alliance:
    What happened to the Alliance Manufacturing Company?
    Alliance stopped production of their rotors in 1994. Norm's Rotor Service purchased their entire parts inventory for the HD-73, U-100, and U-110 rotors and controls.

    Were there 2 models of the HD-73 produced?
    The Alliance HD-73 rotor came in two models. The rotor in both models is the same. The difference is that the earlier model, designated HD-73, had a control unit with a silver, round-style power on-off switch; the later model, designated HD-73-1 had a control unit with a black rocker- style power on-off switch.

    All Control boxes except U-100, U-110 and HDR-300 is $25.00, plus parts and shipping.

    Contact Norm's Rotor Service (e-mail is fastest):
    Toll Free (866) 901-5885
    (205) 982-0550

    73 de Greg
  10. KD7WHQ

    KD7WHQ QRZ Member QRZ Page

    I wasn't intending to come off as huffy, and I hope no offense was taken. There was none intended [​IMG]

    And, it's Will..
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